What adhesive are you using to glue the cork tiles to the MDF? If the tile adhesive dilutes you can prime with that for 100% compatibility, not use PVA .
Hi Astramax. Thank you so much for taking the time to reply. I'm using the Cork tile suppliers recommendation which is Wakol D3540. But I have searched everywhere and can't find any info. My brother says I worry too much and just go for it. But for me there must be a right and wrong answer to my question ie I'm sure the glue will bond well with the cork but will the glue lose any adhesion to the MDF if its not sealed?